- "Agent LT Koenig. Sorry about kicking your candy ass."
- ―LT Koenig to Davis
- "So, what was it like growing up with four of them?"
"There was a lot of crying."
"They picked on you?"
"I picked on them. It was fun. The laundry was disgusting. Enough DNA to make a clone army."
- ―Quake and LT Koenig
Operation Hot Potato
In a attempt to get rid of the Darkhold, Phil Coulson entrusted the book to the Koenigs to dispose of. After receiving the book from Sam Koenig, she then passed it onto Billy Koenig who hid it in the S.H.I.E.L.D vault known as the Labyrinth.
A few days later, while she was listening to her brother, Thurston's concert, she was approached by Phil Coulson due to her brother, Billy being kidnapped. She initially attacked Agent Davis but apologized when she realized they were with S.H.I.E.L.D. As the Koenigs reunited on the Zephyr One, they argued about S.H.I.E.L.D. activities during which their brother Eric died before engaging in a group hug as a sign of reconciliation, where LT punched Billy for letting his guard down. LT then revealed where Billy hid the book and took the team to the Labyrinth.
While at the Labyrinth, the team was attacked by Watchdogs led by Tucker Shockley with Billy as their hostage. This lead into a firefight where she managed to save her brother. Unfortunately, Holden Radcliffe managed to get the Darkhold and ran away. LT returned aboard the Zephyr One, where she made fun of Davis for believing that the Koenigs brothers were Life-Model Decoys. She then left the team with her brothers.
- "Stop being a whiny little bitch!"
- ―LT Koenig to Thurston Koenig
- Expert Combatant : As a S.H.I.E.L.D. special agent, LT Koenig is highly skilled fighter. Despite her short size, she quickly overpowered agent Davis when he and Daisy Johnson came to The Soul Patch to pick her up. She also fiercely knocked out a Watchdog at the Labyrinth.
- I.C.E.R.: As a S.H.I.E.L.D. agent, LT Koenig carried an I.C.E.R., which she used to force her brother Thurson to go onto the Zephyr One for his own protection.
- Eric Koenig † - Brother and Colleague
- Billy Koenig - Brother and Colleague
- Sam Koenig - Brother and Colleague
- Thurston Koenig - Brother
- In the comics, Ilsa Koenig was Eric Koenig's sister and a member of the German Resistance in World War II. She was saved from the Nazis by the Howling Commandos, and dated Nick Fury for a short time.